Root Vegetable Bake

Root vegetable bake is the showstopping mashed-vegetable casserole that earns its place on the Thanksgiving table or any winter Sunday roast. Five vegetables go into the pot: nutty butternut squash, earthy celeriac (the gnarly root form of celery), sweet carrot, fluffy potato, and slightly sharp turnip. They simmer together in salted water until truly tender, about thirty minutes, then drain and mash smooth with milk, margarine, salt, and white pepper.

The finishing trick is the onion topping. Diced onion cooks slowly with chicken broth and a teaspoon of margarine in a separate skillet until the liquid evaporates and the onion turns deep golden, about fifteen minutes. This ‘broth braise’ caramelizes the onion without much added fat. Spread the mashed root vegetables in a casserole, top with the golden onions, and bake at 425°F (220°C) for twenty-five minutes until the top develops a crusty, slightly bronzed surface.

Pro Tips

• Cube every vegetable to roughly the same size so they cook through together. Larger pieces stay raw in the center while smaller ones turn to mush.
• Drain the boiled vegetables really well before mashing. Wet roots make a watery casserole.
• Use white pepper, not black, to keep the casserole pale and elegant. Black pepper specks look like dirt against the cream-colored mash.
• The ‘broth braise’ for the onions is brilliant. Don’t skip it for plain sautéed onions, the deep flavor comes from slowly reducing the broth as it cooks.

Variations

• Swap any of the vegetables for parsnips, rutabaga, or sweet potato.
• Use butter instead of margarine and whole milk or cream for a richer, holiday-worthy version.
• Top with a sprinkle of grated Gruyère or Parmesan in the last ten minutes for a cheesy crust.